Problem: Stephanie ate 3 slices of pie. Tiffany ate 4 slices. If Stephanie ate $\dfrac{3}{8}$ of the pie, what fraction of the pie is remaining?
Answer: If 3 slices represent $\dfrac{3}{8}$ of the pie, there must have been a total of 8 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 7 slices, which leaves 1 out of 8 slices remaining. There is $\dfrac{1}{8}$ of the pie remaining.